Measurement of Ca channel activity of isolated adult rat heart cells using 54Mn.
Measurement of Ca channel activity of isolated adult rat heart cells using 54Mn.
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使用 54Mn 测量离体成年大鼠心脏细胞的 Ca 通道活性。
DOI：
10.1016/0003-9861(89)90327-5
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发表时间：
1989
影响因子：
3.9
通讯作者：
Berkoff,HA
中科院分区：
文献类型：
--
作者：
Haworth,RA;Goknur,AB;Berkoff,HA
成年大鼠离体心脏细胞在1 mmCa的培养液中以5 μmMn孵育，表现出Mn结合的快速期和Mn摄取的缓慢期。通过乙二醇双（β-氨基乙醚）N,N ' -四乙酸对其温度不敏感去除判断，快速期为细胞外结合。缓慢的线性阶段代表细胞摄取，通过洋地黄苷和离子载体A23187的释放来判断。异丙肾上腺素增加了锰吸收的线性速率，并诱导了一些细胞的自发跳动活性。这两种作用均被尼群地平抑制。电刺激悬浮细胞增加细胞对锰的线性吸收速率。异丙肾上腺素增强了这种增加，尼群地平或维拉帕米抑制了这种增加。在异丙肾上腺素存在的情况下，5- 6周龄大鼠的细胞刺激依赖的Mn摄取（每毫克蛋白质）比8- 9个月大的雌性退休繁殖大鼠的细胞更大。在异丙肾上腺素存在的情况下，赖诺定增加了刺激依赖性的锰摄取，而在异丙肾上腺素不存在的情况下则没有。我们的结论是：(i) 54mn的细胞摄取是钙通道功能的一个很好的探针；异丙肾上腺素促进锰通过离体心脏细胞的通道内流；（iii）幼龄大鼠（5-6周）的细胞β-肾上腺素能诱导的Ca通道活性高于成年大鼠（8-9个月）的细胞；（iv） ryanodine在异丙肾上腺素存在下促进Ca通道活性（可能是间接的）。
Isolated adult rat heart cells incubated with 5 μmMn in a medium with 1 mmCa showed a rapid phase of Mn binding plus a slow phase of Mn uptake. The rapid phase was extracellular binding, as judged by its temperature-insensitive removal by ethylene glycol bis(β-aminoethyl ether)N,N′-tetraacetic acid. The slow linear phase represented cellular uptake, as judged by its release with digitonin plus the ionophore A23187. Isoproterenol increased the linear rate of Mn uptake and induced spontaneous beating activity in some cells. Both effects were inhibited by nitrendipine. Electrical stimulation of the cells in suspension increased the linear rate of cellular Mn uptake. The increase was potentiated by isoproterenol, and inhibited by nitrendipine or verapamil. Stimulation-dependent Mn uptake (per milligram protein) was greater for cells from 5- to 6-week-old rats than for 8- to 9-month-old female retired breeder rats, in the presence of isoproterenol. Ryanodine increased the stimulation-dependent Mn uptake in the presence of isoproterenol, but not in its absence. We conclude: (i) that cellular uptake of54Mn is a good probe of Ca channel function; (ii) that isoproterenol promotes Mn influx by the channel in isolated heart cells; (iii) that cells from young rats (5–6 weeks) have a higher β-adrenergically induced Ca channel activity than cells from mature rats (8–9 months); and (iv) that ryanodine promotes Ca channel activity (perhaps indirectly) in the presence of isoproterenol.